The present invention is directed to a directional coupler device for a radar system for coupling the power from a transmitter to a transmitting antenna without the use of a circular coupler. In my previous U.S. Pat. No. 4,673,937, FIG. 2A depicts the transmitter 58 transmitting power through a directional coupler 60 into a circulator/coupler 49 and an RF load 62. The output of the circulator/coupler 49 supplies energy to a receiver 64 and the transmitting/receiving antenna 48.
The circuit described above is discussed fully in the referenced U.S. Pat. No. 4,673,937 and provides an efficient method of transmitting and receiving signals from a radar transmitter. However, the circuit is adversely affected by strong magnetic fields resulting in irregular and/or inaccurate performance.
There has been a continuing and long standing need for a microwave device for a small radar system that solves the aforementioned problem. The coupler of this invention satisfies this need as well as providing other advantages to be described below.